On Thu, Oct 7, 2021 at 1:22 AM Vishal Verma <[email protected]> wrote:
>
> Add libcxl interfaces to allow performinfg label (LSA) manipulations.
> Add a 'cxl_cmd_new_set_lsa' interface to create a 'Set LSA' mailbox
> command payload, and interfaces to read, write, and zero the LSA area on
> a memdev.
>
> Cc: Dan Williams <[email protected]>
> Signed-off-by: Vishal Verma <[email protected]>
> ---
> cxl/lib/private.h | 6 ++
> cxl/lib/libcxl.c | 137 +++++++++++++++++++++++++++++++++++++++++++++
> cxl/libcxl.h | 7 +++
> cxl/lib/libcxl.sym | 4 ++
> 4 files changed, 154 insertions(+)
>
> diff --git a/cxl/lib/private.h b/cxl/lib/private.h
> index 671f12f..89212df 100644
> --- a/cxl/lib/private.h
> +++ b/cxl/lib/private.h
> @@ -79,6 +79,12 @@ struct cxl_cmd_get_lsa_in {
> le32 length;
> } __attribute__((packed));
>
> +struct cxl_cmd_set_lsa {
> + le32 offset;
> + le32 rsvd;
> + unsigned char lsa_data[0];
> +} __attribute__ ((packed));
> +
> struct cxl_cmd_get_health_info {
> u8 health_status;
> u8 media_status;
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index 59d091c..8dd69cf 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -1126,3 +1126,140 @@ CXL_EXPORT int cxl_cmd_get_out_size(struct cxl_cmd
> *cmd)
> {
> return cmd->send_cmd->out.size;
> }
> +
> +CXL_EXPORT struct cxl_cmd *cxl_cmd_new_write_label(struct cxl_memdev *memdev,
> + void *lsa_buf, unsigned int offset, unsigned int length)
> +{
> + struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
> + struct cxl_cmd_set_lsa *set_lsa;
> + struct cxl_cmd *cmd;
> + int rc;
> +
> + cmd = cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_SET_LSA);
> + if (!cmd)
> + return NULL;
> +
> + /* this will allocate 'in.payload' */
> + rc = cxl_cmd_set_input_payload(cmd, NULL, sizeof(*set_lsa) + length);
> + if (rc) {
> + err(ctx, "%s: cmd setup failed: %s\n",
> + cxl_memdev_get_devname(memdev), strerror(-rc));
> + goto out_fail;
> + }
> + set_lsa = (void *)cmd->send_cmd->in.payload;
...the cast is still nagging at me especially when this knows what the
payload is supposed to be. What about a helper per command type of the
form:
struct cxl_cmd_$name *to_cxl_cmd_$name(struct cxl_cmd *cmd)
{
if (cmd->send_cmd->id != CXL_MEM_COMMAND_ID_$NAME)
return NULL;
return (struct cxl_cmd_$name *) cmd->send_cmd->in.payload;
}
> + set_lsa->offset = cpu_to_le32(offset);
> + memcpy(set_lsa->lsa_data, lsa_buf, length);
> +
> + return cmd;
> +
> +out_fail:
> + cxl_cmd_unref(cmd);
> + return NULL;
> +}
> +
> +enum lsa_op {
> + LSA_OP_GET,
> + LSA_OP_SET,
> + LSA_OP_ZERO,
> +};
> +
> +static int lsa_op(struct cxl_memdev *memdev, int op, void **buf,
> + size_t length, size_t offset)
> +{
> + const char *devname = cxl_memdev_get_devname(memdev);
> + struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
> + struct cxl_cmd *cmd;
> + void *zero_buf = NULL;
> + ssize_t ret_len;
> + int rc = 0;
> +
> + if (op != LSA_OP_ZERO && (buf == NULL || *buf == NULL)) {
> + err(ctx, "%s: LSA buffer cannot be NULL\n", devname);
> + return -EINVAL;
> + }
> +
> + /* TODO: handle the case for offset + len > mailbox payload size */
> + switch (op) {
> + case LSA_OP_GET:
> + if (length == 0)
> + length = memdev->lsa_size;
What's the use case to support a default size for get? If someone
wants to do a zero length lsa_op shouldn't that just return immediate
success just like 0 length read(2)?
> + cmd = cxl_cmd_new_read_label(memdev, offset, length);
> + if (!cmd)
> + return -ENOMEM;
> + rc = cxl_cmd_set_output_payload(cmd, *buf, length);
> + if (rc) {
> + err(ctx, "%s: cmd setup failed: %s\n",
> + cxl_memdev_get_devname(memdev), strerror(-rc));
> + goto out;
> + }
> + break;
> + case LSA_OP_ZERO:
> + if (length == 0)
This one makes sense because the caller just wants the whole area zeroed.
> + length = memdev->lsa_size;
> + zero_buf = calloc(1, length);
> + if (!zero_buf)
> + return -ENOMEM;
> + buf = &zero_buf;
> + /* fall through */
> + case LSA_OP_SET:
...and if length == 0 here there's no need to go any further, we're done.
> + cmd = cxl_cmd_new_write_label(memdev, *buf, offset, length);
> + if (!cmd) {
> + rc = -ENOMEM;
> + goto out_free;
> + }
> + break;
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + rc = cxl_cmd_submit(cmd);
> + if (rc < 0) {
> + err(ctx, "%s: cmd submission failed: %s\n",
> + devname, strerror(-rc));
> + goto out;
> + }
> +
> + rc = cxl_cmd_get_mbox_status(cmd);
> + if (rc != 0) {
> + err(ctx, "%s: firmware status: %d\n",
> + devname, rc);
> + rc = -ENXIO;
> + goto out;
> + }
> +
> + if (op == LSA_OP_GET) {
> + ret_len = cxl_cmd_read_label_get_payload(cmd, *buf, length);
> + if (ret_len < 0) {
> + rc = ret_len;
> + goto out;
> + }
> + }
> +
> + /*
> + * TODO: If writing, the memdev may need to be disabled/re-enabled to
> + * refresh any cached LSA data in the kernel.
> + */
I think we're sufficiently protected by the nvdimm-bridge up/down
dependency. I.e. if the above commands actually worked then nothing
should have had the labels cached in the kernel.
After fixing the the length == 0 case you can add:
Reviewed-by: Dan Williams <[email protected]>
